Method of placing a component by means of a placement device at a desired position on a substrate holder, and device suitable for performing such a method

ABSTRACT

A method places a component at a desired position on a substrate by means of a placement device. The component is transported to an intermediate position above the desired position and a position difference between the intermediate position and the desired position is determined by means of a camera and a processor. Subsequently, the component is transported to the desired position on the substrate, making use of the position difference. The camera, which is arranged at the side of the component opposite the component&#39;s side facing the substrate, takes an image of at least the portion of the substrate that includes the desired position as well as the placement device.

The invention relates to a method of placing a component at a desiredposition on a substrate by means of a placement device, wherein thecomponent is displaced by means of the placement device to anintermediate position above the desired position on the substrate,whereafter a difference between the intermediate position of thecomponent and the desired position of the component on the substrate isdetermined by means of at least a camera and a processor, where afterthe component is displaced by means of the placement device on the basisof the difference between the intermediate position and the desiredposition with respect to the substrate and is positioned at the desiredposition on the substrate.

The invention also relates to a device suitable for performing such amethod.

In such a method and device, known from international patent applicationWO 97/02708, a component is taken up from a component supply device,while using a placement device. A substrate is brought to apredetermined position by means of a substrate holder. Together with thecomponent, the placement device is displaced to the intermediateposition above the desired position on the substrate. Subsequently, analignment device provided with at least a camera, an optical system andillumination devices is positioned between the placement device and thesubstrate. The position of the component as well as the position of thelocation on the substrate on which the component must be placed isdetermined by means of the alignment device and the processor connectedthereto. Subsequently, it is determined by means of the processorwhether the component is exactly situated above the desired position onthe substrate or whether there are deviations between the intermediateposition and the desired position.

Subsequently, the alignment device is removed from the area between theplacement device and the substrate, whereafter the placement device isdisplaced with reference to given deviations between the intermediateposition and the desired position, such that the component is positionedat the desired position of the substrate.

Although accurate placement of the component on the substrate isguaranteed by means of such a method and device, it is a relativelytime-consuming matter to provide the alignment device between theplacement device and the substrate and remove it again. Moreover, theplacement device should be situated at a relatively large distance abovethe substrate so as to provide sufficient space for positioning thealignment device between the placement device and the substrate. Thisrelatively large distance may lead to errors during placement. Moreover,it takes a relatively long time to bridge this distance.

It is an object of the invention to provide a method with which thecomponent can be positioned at a desired position on the substrate in arelatively accurate and rapid manner.

In the method according to the invention, this object is achieved inthat an image of at least a part of the substrate comprising the desiredposition and of the placement device supporting the component is made bymeans of the camera from a side of the component remote from thesubstrate.

By making an image from a side of the component remote from thesubstrate, the camera does not need to be accommodated in the spacebetween the placement device and the substrate. Consequently, theplacement device can be arranged closer to the substrate before theimage is made. Since the placement device as well as the substrate arevisible on the image, the relative mutual position between the placementdevice and the substrate can be directly determined.

In the method described in international patent application WO 97/02708cited hereinbefore, two images are made, or two images are imaged one onthe other by means of an optical system. In the latter case, the opticalsystem should be relatively accurate so as to guarantee an accurateprojection of the two superposed images.

In the method according to the invention, an image of both the placementdevice and the substrate is made directly.

When the image is being made, the placement device may be situated at arelatively short distance above the substrate so that possibledeviations between the intermediate position of the component and thedesired position of the component on the substrate can be determinedwith reference to the image in a relatively accurate manner.Subsequently, the component can be placed on the substrate relativelyrapidly, because the distance to be bridged between the intermediateposition and the desired position is relatively small.

An embodiment of the method according to the invention is characterizedin that the relative position of the placement device with respect tothe desired position of the component on the substrate is determinedfrom the image.

By determining the relative position of the placement device withrespect to the desired position of the component on the substrate withreference to the image, the placement device can be displaced relativelyrapidly and with relatively little accuracy to the part of the substratecomprising the desired position, whereafter the placement device can beaccurately positioned after a relative position of the placement devicewith respect to the substrate has been determined.

A further embodiment of the method according to the invention ischaracterized in that, prior to displacing the placement device to theintermediate position situated above the desired position, the relativeposition of the component with respect to the placement device isdetermined, whereafter the relative position of the placement devicewith respect to the substrate is determined with reference to the image,and subsequently the relative position of the component with respect tothe substrate is determined with reference to the relative positions ofthe component with respect to the placement device and of the placementdevice with respect to the desired position on the substrate.

This provides the possibility of accurately determining the mutualposition of the component with respect to the substrate with referenceto the relative positions of the placement device with respect to thecomponent and the substrate.

A further embodiment of the method according to the invention ischaracterized in that the component is also visible on the image of atleast the part of the substrate, wherein the relative position of thecomponent with respect to the substrate is directly determined withreference to the image.

If the component is also visible on the image, it is possible todirectly determine the relative position of the component with respectto the substrate, so that it is no longer necessary to determine therelative position of the placement device with respect to the componentor the substrate.

The invention also relates to a device provided with a substratecarrier, a placement device which is displaceable with respect to thesubstrate carrier, at least a camera, a processor and an optical systemarranged between the camera and the placement device.

The device according to the invention is characterized in that at leasta part of the placement device and at least a part of a substratesupported, in operation, by the substrate carrier can be imaged in thecamera by means of the optical system.

Since both the placement device and the substrate can be simultaneouslyimaged in the camera, the relative position of the placement device withrespect to the substrate or of the component, supported by the placementdevice, with respect to the substrate can be determined in a relativelysimple manner.

An embodiment of the device according to the invention is characterizedin that the placement device is also provided with at least one mark.

The mark guarantees a satisfactory detectability of the placementdevice.

These and other aspects of the invention are apparent from and will beelucidated with reference to the embodiments described hereinafter.

In the drawings:

FIGS. 1A to 1C show a device according to the invention during differentstages of placing a component on a substrate,

FIG. 2 shows an image made by means of the device shown in FIG. 1,

FIG. 3 shows a second embodiment of a device according to the invention,

FIG. 4 shows a third embodiment of a device according to the invention.

FIGS. 1A to 1C show a device 1 according to the invention duringdifferent stages of placing a component 2 on a substrate 3.

The placement device 1 has a tube 5 extending along a centerline 4,which tube has a nozzle 6 at its lower side. Sub-atmospheric pressurecan be provided in the tube 5 and the nozzle 6 for taking up acomponent. The tube 5 has a plurality of marks 7 regularly distributedon the circumference. The side of the nozzle 6 facing the marks 7 isprovided with mirrors 8. The tube 5 extends on a side remote from thenozzle 6 through a mirror 9 arranged at an angle of 45° with respect tothe centerline 4. A second mirror 10 extending parallel to the mirror 9is spaced apart from the mirror 9. A lens system 11 is spaced apart fromthe mirror 10. A camera 12 is arranged on a side of the lens system 11remote from the mirror 10. Together with the mirrors 9, 10, the lenssystem 11 and the camera 12 the placement device 1 can be displaced inand opposite to the directions denoted by the arrows X₁, Y₁ and Z₁. Thedisplacement is effected by means of a known displacement device (notshown). Together with the nozzle 6, the tube 5 of the placement device 1is displaceable by means of actuators 13, arranged proximate to themirror 9, through relatively small distances with respect to the camera12 in and opposite to the directions denoted by arrows X₂, Y₂ and Z₂,and is rotatable around the centerline 4 in and opposite to thedirections denoted by arrow v.

As is further visible in FIG. 1A, a second camera 14 and an opticalsystem 15 situated between the nozzle 6 and the camera 14 are arrangedon a side of the nozzle 6 remote from the camera 12.

The operation of the device according to the invention will now beexplained with reference to FIGS. 1A to 1C.

Together with the camera 12, the placement device 1 is displaced to acomponent supply device (not shown) where a component 2 is taken up withvacuum by means of the nozzle 6. Subsequently, the component 2 isdisplaced in the directions denoted by X₁, Y₁ and Z₁ by means of theplacement device 1 until the component 2 is situated above the camera14. Subsequently, the position of component 2 with respect to the nozzle6 and thus the placement device 1 is determined (FIG. 1A) by means ofthe camera 14 and a processor (not shown) connected thereto.

After the position of the component 2 with respect to the placementdevice 1 has been determined, the placement device 1 is displacedtogether with the camera 12 in the X₁, Y₁ and Z₁ directions until thecomponent 2 is situated in an intermediate position, shown in FIG. 1B,above the substrate 3 proximate to the desired position on the substrate3. An image of a part of the substrate 3 on which the component 2 is tobe positioned is now made by means of the camera 12. The tube 5 situatedin the optical path 16, the marks 7 on this tube and the nozzle 6 willalso be visible on the image. At the instant when an image is made bymeans of the camera 12, the distance d between the marks 7 and themirrors 8 is preferably equal to the distance between the mirrors 8 andthe substrate 3 so that, optically, the mirror images 7′ of the marks 7are situated, as it were, on the substrate 3. With a relatively smalldepth of focus of the camera 12, an accurate image can thus still bemade. Subsequently, the orientation of the substrate 3 and notably thepart on which the component is to be positioned is determined withrespect to the marks 7′ and hence the placement device 1 by means of aprocessor and with reference to the image 12 obtained from the camera12.

Subsequently, the relative position of the component 2 with respect tothe substrate 3 is computed by means of the processor with reference tothe previously determined orientation of the component 2 with respect tothe placement device 1 and the now computed orientation of the marks 7′and hence the placement device 1 with respect to the substrate 3.

In the situation shown in FIG. 1B, the component 2 is situated in theintermediate position at a distance) in the X direction of the desiredposition on the substrate 3.

After the relative position of the component 2 has been computed withrespect to the substrate 3, the tube 5 is displaced in the downwarddirection Z₂ with respect to the camera 12, while also a displacement)in the X₂ direction and, if desired, a required correction in the Y₂direction is performed by means of the actuators 13. The tube 5 isdisplaced in the Z₂ direction until the component 2 is positioned on thesubstrate 3. Subsequently, the component 2 is released by the nozzle 6and the tube 5 is replaced to its original position in the placementdevice 1.

During displacement of the tube 5 in the downward direction, it ispossible to continuously make images by means of the camera 12 so thatit is also possible during this downward displacement of the tube 5 tocompute a supplementary correction in the X₂ or Y₂ direction and performthis correction by means of the actuators 13.

FIG. 2 shows an image 20 made by means of a camera 12, in which image apart of the substrate 3 as well as the tube 5, the nozzle 6 and themirror images 7′ of the marks 7 are visible. The substrate 3 is providedwith a plurality of electric wires 21 with respect to which thecomponent 2 to be placed must be aligned. The intermediate position ofthe component 2 in the situation shown in FIG. 1B with respect to thedesired position on the substrate can be determined with reference tothe image 20.

FIG. 3 shows a second embodiment of a device 30 according to theinvention which, instead of mirrors 9, 10 and an optical system 11, isprovided with a plurality of glass fibers 31, whose first ends areconnected to a camera 32 and the ends remote from the camera 32 face thesubstrate 3. Such a camera 32 also provides the possibility ofdetermining the relative position of the tube 5 of the placement device30 with respect to the substrate 3.

FIG. 4 shows a third embodiment of a device 40 according to theinvention, in which the relative position of the tube 5 of the placementdevice 40 with respect to the substrate 3 is determined by means of aplurality of cameras 41 before component 2 is positioned on thesubstrate 3.

If the component 2 is relatively large, i.e. if it is larger than thenozzle 6, it is alternatively possible to directly obtain an image bymeans of the camera 12, 32, 41, on which image both a part of theplacement device, the component and a part of the substrate 3 arevisible. The relative position of the component 2 with respect to thesubstrate 3 can then be directly determined with reference to thisimage.

When determining the position of the component with respect to thenozzle 6, use can be made of a fixed marking plate, and an image of themarking plate and a component positioned above this plate issimultaneously made by means of the camera 14, while an image of themarling plate and the marks 7 is made by means of camera 12. Theposition of the component with respect to the marks is subsequentlydetermined from both images.

It is alternatively possible to use light-emitting diodes (LED) orlight-conducting fibers as marks 7.

Components can be placed relatively rapidly by means of the device andmethod according to the invention. Moreover, the entire device may berelatively inaccurate, provided that a desired accuracy can be realizedduring actual placement.

1-10. (canceled)
 11. A method of placing a component at a desiredposition on a substrate by means of a placement device, the methodcomprising the steps of: supporting the component using the placementdevice; displacing the component by means of the placement device to anintermediate position above the desired position on the substrate;determining a difference between the intermediate position and thedesired position of the component on the substrate by means of at leasta camera and a processor, the step of determining the differencecomprising the step of: creating, from a side of the component remotefrom the substrate, an image of at least a part of the substratecomprising the desired position and the placement device supporting thecomponent; displacing the component by means of the placement device onthe basis of the difference between the intermediate position and thedesired position with respect to the substrate; positioning thecomponent at the desired position on the substrate.
 12. The methodaccording to claim 11, wherein a relative position of the placementdevice with respect to the desired position of the component on thesubstrate is determined from the image.
 13. The method according toclaim 11, wherein, prior to displacing the placement device to theintermediate position situated above the desired position, the methodfurther comprises the step of: determining a relative position of thecomponent with respect to the placement device; determining, withreference to the image, a relative position of the placement device withrespect to the desired position on the substrate; and determining, withreference to the relative positions of the component with respect to theplacement device and the placement device with respect to the desiredposition on the substrate, a relative position of the component withrespect to the substrate.
 14. The method according to claim 11, whereinthe step of creating, from a side of the component remote from thesubstrate, an image of at least a part of the substrate comprising thedesired position and the placement device supporting the componentcomprises the step of: imaging, from a side of the component remote fromthe placement device, the component and the placement device using asecond camera; and determining, with reference to the image, a relativeposition of the component with respect to the placement device.
 15. Themethod according to claim 11, wherein the component is also visible onthe image of at least the part of the substrate, and wherein the methodfurther comprises the step of: determining a relative position of thecomponent with respect to the substrate with reference to the image. 16.A device comprising: a substrate carrier; a placement device that isdisplaceable with respect to the substrate carrier; at least one camera;a processor; and an optical system arranged between the camera and theplacement device, wherein the camera, by means of the optical system, isconfigured to image at least a part of the placement device and at leasta part of a substrate supported, in operation, by the substrate carrier.17. The device according to claim 16, wherein the device is configuredto perform the method of claim
 1. 18. The device according to claim 16,wherein the placement device comprises at least one mark.
 19. The deviceaccording to claim 18, wherein the placement device further comprises amirror arranged between the at least one mark and the substrate carrier.20. The device according to claim 19, wherein a distance between themirror and the substrate supported, in operation, by the substratecarrier is substantially equal to a distance between the mirror and themark during imaging of the substrate in the camera.
 21. The deviceaccording to claim 16, wherein the placement device comprises a vacuumtube that is displaceable with respect to the placement device.
 22. Adevice comprising: a substrate carrier configured to support asubstrate; a placement device that is displaceable with respect to thesubstrate carrier, the placement device comprising: at least one mark;and a mirror arranged between the at least one mark and the substratecarrier; at least one camera; a processor; and an optical systemarranged between the camera and the placement device, wherein thecamera, by means of the optical system, is configured to image at leasta part of the placement device and at least a part of the substrate,wherein a distance between the mirror and the substrate is substantiallyequal to a distance between the mirror and the mark during imaging ofthe substrate in the camera.
 23. The device according to claim 22,wherein the placement device further comprises a vacuum tube that isdisplaceable with respect to the placement device.